U.S. Pat. No. 3,469,188 A (Hall) describes a circuit for use with lightning arresters to provide a measure of the grading current and leakage current associated with the arresters as well as to count the number of surges occurring through the arresters and also in U.S. Pat. No. 4,338,648 (Subbarao) describes gapless discharge counter for lightning arresters.
The discharge counter is connected between the surge arrester and ground, monitors the steady state current by means of an ammeter and records the number of discharges by means of a capacitor, cyclometer coil, and a recorder. Regarding These parameters the accuracy or having malfunction in lightning arresters can be determined.
The lightning arresters are used in substations to protect the equipment against the excessive voltage that are produced because of surge or switching. Considering that there was no device for testing the accuracy of discharge counter function, there was no insurance that the counter worked well or not. Therefore the accuracy of the lightning arrester function wasn't specified because of the lack of a secure and accurate monitoring done by discharge counter. It's very important to know that if the lightning arresters don't work well, a lot of irreparable accidents can occur to the system. So; the accuracy of the discharge counters function is very important. Therefore inventing a device for testing the accuracy of discharge counters function was seen very important.